Abstract: Objective To study the effect of allitridum on rapidly delayed rectifier potassium current (IKr) in HEK293 cell line.
Methods HEK293 cells were transiently transfected with HERG channel cDNA plasmid pcDNA3.1 via Lipofectamine.
Allitridum was added to the extracellular solution by partial perfusion after giga seal at the final concentration of 30 μmol/L.
Whole-cell patch clamp technique was used to record the HERG currents and gating kinetics before and after allitridum
exposure at room temperature. Results The amplitude and density of IHERG were both suppressed by allitridum in a
voltage-dependent manner. In the presence of allitridum, the peak current of IHERG was reduced from 73.5±4.3 pA/pF to 42.1±3.6
pA/pF at the test potential of +50 mV (P<0.01). Allitridum also concentration-dependently decreased the density of the IHERG.
The IC50 of allitridum was 34.74 μmol/L with a Hill coefficient of 1.01. Allitridum at 30 μmol/L caused a significant positive
shift of the steady-state activation curve of IHERG and a markedly negative shift of the steady-state inactivation of IHERG, and
significantly shortened the slow time constants of IHERG deactivation. Conclusion Allitridum can potently block IHERG in HEK293
cells, which might be the electrophysiological basis for its anti-arrhythmic action.